text: //------------------------------------------------------------------------------
  /*
      This file is part of rippled: https://github.com/ripple/rippled
      Copyright (c) 2012, 2013 Ripple Labs Inc.
  
      Permission to use, copy, modify, and/or distribute this software for any
      purpose  with  or without fee is hereby granted, provided that the above
      copyright notice and this permission notice appear in all copies.
  
      THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
      WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
      MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
      ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
      WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
      ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
      OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
  //==============================================================================
  
  #include <BeastConfig.h>
  #include <ripple/app/ledger/OrderBookDB.h>
  #include <ripple/app/ledger/LedgerMaster.h>
  #include <ripple/app/main/Application.h>
  #include <ripple/basics/Log.h>
  #include <ripple/core/Config.h>
  #include <ripple/core/JobQueue.h>
  #include <ripple/protocol/Indexes.h>
  
  namespace ripple {
  
  OrderBookDB::OrderBookDB (Application& app, Stoppable& parent)
      : Stoppable ("OrderBookDB", parent)
      , app_ (app)
      , mSeq (0)
      , j_ (app.journal ("OrderBookDB"))
  {
  }
  
  void OrderBookDB::invalidate ()
  {
      std::lock_guard <std::recursive_mutex> sl (mLock);
      mSeq = 0;
  }
  
  void OrderBookDB::setup(
      std::shared_ptr<ReadView const> const& ledger)
  {
      {
          std::lock_guard <std::recursive_mutex> sl (mLock);
          auto seq = ledger->info().seq;
  
          // Do a full update every 256 ledgers
          if (mSeq != 0)
          {
              if (seq == mSeq)
                  return;
              if ((seq > mSeq) && ((seq - mSeq) < 256))
                  return;
              if ((seq < mSeq) && ((mSeq - seq) < 16))
                  return;
          }
  
          JLOG (j_.debug())
              << "Advancing from " << mSeq << " to " << seq;
  
          mSeq = seq;
      }
  
      if (app_.config().PATH_SEARCH_MAX == 0)
      {
          // nothing to do
      }
      else if (app_.config().standalone())
          update(ledger);
      else
          app_.getJobQueue().addJob(
              jtUPDATE_PF, "OrderBookDB::update",
              [this, ledger] (Job&) { update(ledger); });
  }
  
  void OrderBookDB::update(
      std::shared_ptr<ReadView const> const& ledger)
  {
      hash_set< uint256 > seen;
      OrderBookDB::IssueToOrderBook destMap;
      OrderBookDB::IssueToOrderBook sourceMap;
      hash_set< Issue > ZXCBooks;
  
      JLOG (j_.debug()) << "OrderBookDB::update>";
  
      if (app_.config().PATH_SEARCH_MAX == 0)
      {
          // pathfinding has been disabled
          return;
      }
  
      // walk through the entire ledger looking for orderbook entries
      int books = 0;
  
      try
      {
          for(auto& sle : ledger->sles)
          {
              if (isStopping())
              {
                  JLOG (j_.info())
                      << "OrderBookDB::update exiting due to isStopping";
                  std::lock_guard <std::recursive_mutex> sl (mLock);
                  mSeq = 0;
                  return;
              }
  
              if (sle->getType () == ltDIR_NODE &&
                  sle->isFieldPresent (sfExchangeRate) &&
                  sle->getFieldH256 (sfRootIndex) == sle->key())
              {
                  Book book;
                  book.in.currency.copyFrom(sle->getFieldH160(
                      sfTakerPaysCurrency));
                  book.in.account.copyFrom(sle->getFieldH160 (
                      sfTakerPaysIssuer));
                  book.out.account.copyFrom(sle->getFieldH160(
                      sfTakerGetsIssuer));
                  book.out.currency.copyFrom (sle->getFieldH160(
                      sfTakerGetsCurrency));
  
                  uint256 index = getBookBase (book);
                  if (seen.insert (index).second)
                  {
                      auto orderBook = std::make_shared<OrderBook> (index, book);
                      sourceMap[book.in].push_back (orderBook);
                      destMap[book.out].push_back (orderBook);
                      if (isZXC(book.out))
                          ZXCBooks.insert(book.in);
                      ++books;
                  }
              }
          }
      }
      catch (const SHAMapMissingNode&)
      {
          JLOG (j_.info())
              << "OrderBookDB::update encountered a missing node";
          std::lock_guard <std::recursive_mutex> sl (mLock);
          mSeq = 0;
          return;
      }
  
      JLOG (j_.debug())
          << "OrderBookDB::update< " << books << " books found";
      {
          std::lock_guard <std::recursive_mutex> sl (mLock);
  
          mZXCBooks.swap(ZXCBooks);
          mSourceMap.swap(sourceMap);
          mDestMap.swap(destMap);
      }
      app_.getLedgerMaster().newOrderBookDB();
  }
  
  void OrderBookDB::addOrderBook(Book const& book)
  {
      bool toZXC = isZXC (book.out);
      std::lock_guard <std::recursive_mutex> sl (mLock);
  
      if (toZXC)
      {
          // We don't want to search through all the to-ZXC or from-ZXC order
          // books!
          for (auto ob: mSourceMap[book.in])
          {
              if (isZXC (ob->getCurrencyOut ())) // also to ZXC
                  return;
          }
      }
      else
      {
          for (auto ob: mDestMap[book.out])
          {
              if (ob->getCurrencyIn() == book.in.currency &&
                  ob->getIssuerIn() == book.in.account)
              {
                  return;
              }
          }
      }
      uint256 index = getBookBase(book);
      auto orderBook = std::make_shared<OrderBook> (index, book);
  
      mSourceMap[book.in].push_back (orderBook);
      mDestMap[book.out].push_back (orderBook);
      if (toZXC)
          mZXCBooks.insert(book.in);
  }
  
  // return list of all orderbooks that want this issuerID and currencyID
  OrderBook::List OrderBookDB::getBooksByTakerPays (Issue const& issue)
  {
      std::lock_guard <std::recursive_mutex> sl (mLock);
      auto it = mSourceMap.find (issue);
      return it == mSourceMap.end () ? OrderBook::List() : it->second;
  }
  
  int OrderBookDB::getBookSize(Issue const& issue) {
      std::lock_guard <std::recursive_mutex> sl (mLock);
      auto it = mSourceMap.find (issue);
      return it == mSourceMap.end () ? 0 : it->second.size();
  }
  
  bool OrderBookDB::isBookToZXC(Issue const& issue)
  {
      std::lock_guard <std::recursive_mutex> sl (mLock);
      return mZXCBooks.count(issue) > 0;
  }
  
  BookListeners::pointer OrderBookDB::makeBookListeners (Book const& book)
  {
      std::lock_guard <std::recursive_mutex> sl (mLock);
      auto ret = getBookListeners (book);
  
      if (!ret)
      {
          ret = std::make_shared<BookListeners> ();
  
          mListeners [book] = ret;
          assert (getBookListeners (book) == ret);
      }
  
      return ret;
  }
  
  BookListeners::pointer OrderBookDB::getBookListeners (Book const& book)
  {
      BookListeners::pointer ret;
      std::lock_guard <std::recursive_mutex> sl (mLock);
  
      auto it0 = mListeners.find (book);
      if (it0 != mListeners.end ())
          ret = it0->second;
  
      return ret;
  }
  
  // Based on the meta, send the meta to the streams that are listening.
  // We need to determine which streams a given meta effects.
  void OrderBookDB::processTxn (
      std::shared_ptr<ReadView const> const& ledger,
          const AcceptedLedgerTx& alTx, Json::Value const& jvObj)
  {
      std::lock_guard <std::recursive_mutex> sl (mLock);
      if (alTx.getResult () == tesSUCCESS)
      {
          // For this particular transaction, maintain the set of unique
          // subscriptions that have already published it.  This prevents sending
          // the transaction multiple times if it touches multiple ltOFFER
          // entries for the same book, or if it touches multiple books and a
          // single client has subscribed to those books.
          hash_set<std::uint64_t> havePublished;
  
          // Check if this is an offer or an offer cancel or a payment that
          // consumes an offer.
          // Check to see what the meta looks like.
          for (auto& node : alTx.getMeta ()->getNodes ())
          {
              try
              {
                  if (node.getFieldU16 (sfLedgerEntryType) == ltOFFER)
                  {
                      SField const* field = nullptr;
  
                      // We need a field that contains the TakerGets and TakerPays
                      // parameters.
                      if (node.getFName () == sfModifiedNode)
                          field = &sfPreviousFields;
                      else if (node.getFName () == sfCreatedNode)
                          field = &sfNewFields;
                      else if (node.getFName () == sfDeletedNode)
                          field = &sfFinalFields;
  
                      if (field)
                      {
                          auto data = dynamic_cast<const STObject*> (
                              node.peekAtPField (*field));
  
                          if (data &&
                              data->isFieldPresent (sfTakerPays) &&
                              data->isFieldPresent (sfTakerGets))
                          {
                              // determine the OrderBook
                              Book b{data->getFieldAmount(sfTakerGets).issue(),
                                  data->getFieldAmount(sfTakerPays).issue()};
  
                              auto listeners = getBookListeners(b);
                              if (listeners)
                              {
                                  listeners->publish(jvObj, havePublished);
                              }
                          }
                      }
                  }
              }
              catch (std::exception const&)
              {
                  JLOG (j_.info())
                      << "Fields not found in OrderBookDB::processTxn";
              }
          }
      }
  }
  
  } // ripple
  